Field of the Invention
The present invention relates to resolvers, and specifically relates to a structure of a terminal portion having terminal pins around which an end portion of a winding wire of a resolver is wound.
Description of Related Art
Resolvers are known as a means for detecting the rotation angle of a subject. For example, a resolver may be used as a sensor for detecting the rotation angle of an electric motor that is installed in electric cars, hybrid cars, etc. In this case, the resolver includes a rotor that is fixed to a rotating shaft of a motor and rotated therewith and a stator that is fixed to a housing and disposed outside the rotor. When the rotor rotates, the size of an air gap formed between the rotor and the stator changes, and a voltage corresponding to the change is induced in a measuring coil of the stator side, whereby measured output is generated. The measured output corresponds to the rotation angle of the rotor, and the rotation angle of the motor is measured.
A rotor of a resolver has a structure in which multiple circular rotor cores having plural projections radially projecting outward are layered. A stator is disposed outside the rotor. The stator has a structure in which plural stator cores having plural salient poles radially projecting inward from a circular yoke are axially layered. Two insulators are attached to the layered stator cores from both axial sides thereof. An excitation winding wire and an output winding wire are wound around the salient poles via the insulators. The output winding wire is composed of a winding wire outputting sine signals and a winding wire outputting cosine signals that have a phase differing by 90 degrees relative to the sine signals. The end portions of the excitation winding wire and the output winding wire are wound around terminal pins and are electrically connected thereto. The terminal pins are embedded in a terminal support that is integrally formed with the insulator. As such a resolver, a disclosure of, for example, Japanese Unexamined Patent Application Laid-open No. 2011-232213 is known.
In the resolver disclosed in the above document, a connecting means for connecting an end portion of a winding wire to a terminal pin is not specified. In general, connecting of an end portion of a winding wire to a terminal pin is performed such that the end portion of the winding wire is wound around the terminal pin, then the wound portion is fixed by solder or welding.
When the end portion of the winding wire as shown in the above document is wound around the terminal pin, then the wound portion is welded by a welding method such as TIG welding, etc., and is electrically connected to the terminal pin, a portion of a copper wire in the welded portion of the end portion of the winding wire is exposed. If the resolver in the above condition is used in an environment in which water drops adhere or corrosive elements such as sulfides included in an engine oil or an automatic transmission fluid exist, the exposed portion of copper wire is corroded, conduction trouble caused by breaking or corrosion of wire may occur.
In view of such circumstances, it is an object of the present invention to provide a technique in which an end portion of a winding wire is fixed to a terminal pin by welding, and the like, and corrosion of the end portion of the wound wire can be prevented even if the resolver is used in an environment having corrosive elements.